This proposal seeks five years of R01 award support for cross-national comparative analyses of already gathered data on drug dependence epidemiology, the stages of drug involvement leading up to drug dependence, and sequelae of drug dependence, including remission, recovery, treatment, and suspected adverse consequences (e.g., psychiatric disturbances, and effects on social adaptation in school, work, and family life). The general population epidemiological survey data to be analyzed now are being gathered as part of the World Mental Health survey initiative, with currently 28 participating countries, including 16 countries with nationally representative samples of household residents and 12 countries with regionally representative samples. The proposed NIDA-supported research team for data analysis and scientific writing is led by Professors Jim Anthony (Johns Hopkins University) and Professor Ron Kessler (Harvard University). Working in coordination, during Year 01, the primary responsibility of the Harvard team is master data file creation and documentation responsibilities, including documentation of sampling frames and procedures, sampling weights, etc., with the Hopkins team focused upon creation of constructed variables for NIDA-oriented drug dependence analyses and assembly of ancillary elements of information that will help describe the country-level context of drug involvement in each of the participating countries (e.g., information about alcohol, tobacco, illegal drug, and medicinal drug availability by prescription or over the counter; availability of local inhalant drugs).The five year analysis and scientific writing plan will provide an enhanced view of the international comparative epidemiology of drug use and drug dependence problems, guided by a set of three operational aims and five subject-matter aims, each of which corresponds with the five main rubics in a conceptual model for epidemiologieal research on drug involvement and drug dependence. The main research questions to be answered in this cross-national and comparative study are: (1) Within the populations under study, how many are affected (e.g., as cases of drug dependence)? (2) Within these populations, where are the affected cases most likely to be found? (3) What accounts for some individuals to become cases while others do not become cases? (4) What are the causal mechanisms that drive the pathogenesis and etiology of drug dependence and its consequences in the form of psychiatric disturbances and social adaptation, and (5) What might we do to prevent and control drug dependence (e.g., by increasing the ratio of treated/untreated cases, and through primary care outreach)?